Fluid filter system and related method

ABSTRACT

A system includes a tank with a lower chamber spaced from an outlet or upper chamber by a confinement deck. The deck includes one or more sockets for receiving one or more filter units. The lower chamber of the tank acts as a pretreatment sump to remove floating and nonfloating particulates, reducing the load on the filter units. The filter units are configured for radial and/or upward flow of the fluid from the lower chamber. The filter units may be removed for ease of tank maintenance and replacement of filters.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims the priority benefit of U.S. provisionalpatent application Ser. No. 60/590,776, filed Jul. 23, 2004, entitled“FLUID FILTER SYSTEM AND RELATED METHOD” of the same named inventors.The entire contents of that prior application are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to systems for filtering contaminants fromfluids such as drain water and stormwater. More particularly, thepresent invention relates to a filter system and related method forremoving contaminants from a fluid stream by forcing upward and/orradial flow of the fluid through the filter means.

2. Description of the Prior Art

Fluid transfer systems have been and will remain an important aspect ofmunicipal services and commercial facilities management. The protectionof ground water and natural bodies of water requires systems fordiverting and/or treating water that contacts roadways, parking lots,and other man made structures. If such diversion or treatment systemsare not provided, particulate and contaminants located on or formingpart of such structures may be carried by drain water or stormwater tothe natural water bodies and contaminate them. Local, state and federallaws and rules require municipalities, businesses, and in someinstances, private entities, to establish means to reduce particulateand dissolved pollutant levels permissibly transferred to natural bodiesof water from property under their control. Particular requirements mayvary from jurisdiction to jurisdiction, but all are likely to becomemore stringent.

Previously, municipal water transfer and treatment facilities providedthe only mechanism for diverting contaminated water away from naturalbodies of water, either for holding or treatment for subsequent transferto natural settings. In general, that process involved, and continues toinvolve, the establishment of a system of drains, such as in a parkinglot or at a street curb, by which water enters a system of pipeconduits. Eventually, the water received from the drains reaches eithera final outlet destination or is directed to a treatment system forcontaminant removal. For purposes of the description of the presentinvention, “contaminated water” is to be understood to mean any waterincluding floating particulate, such as Styrofoam™ containers and oil,for example; non-floating particulate, such as sand and silt, forexample; and suspended and dissolved contaminants, such as fine solids,oil, grease, organic contaminants including fertilizers, herbicides, andpesticides, and metals, for example.

Land development produces increased quantities of drain water andstormwater runoff, resulting in increased strain on existing watertransfer and treatment infrastructure and an increased likelihood ofnatural water contamination. In an effort to reduce the impact ofdevelopment on natural resources and municipal services, initialupstream fluid treatment has become a requirement in many landdevelopment, restoration and repair projects. That is, requirements invarious forms have been established to ensure that before contaminatedwater enters the municipal water transfer and/or treatment system or anatural body of water, it must be treated in a manner that reduces thelevel of contaminants entering the municipal system or the natural bodyof water. Therefore, most new land development plans and upgrades toexisting paved surfaces involve the insertion of a preliminaryseparation system, generally for connection to the municipalwater-handling infrastructure. In other cases, the outflow from theseparation system may be transferred directly to a natural body ofwater.

Any preliminary separation system must be designed with the capabilityto receive fluid flowing in at a wide range of rates. For example, amild rainfall resulting in rain accumulation of less than 0.25 inchesover a span of 24 hours produces a relatively low flow rate through thesystem. On the other hand, for example, a torrential rainfall resultingin rain accumulation of more than two inches over a span of three hoursproduces relatively high flow rates through the system. It is desirable,then, to have a separation system capable of handling variable fluidflow rates with reduced likelihood of backup and flooding of the surfaceabove.

In addition to having a reasonable fluid flow throughput capacity, theseparation system must be capable of performing the separation functionfor which it is intended. Relatively large floating particulate andrelatively heavy non-floating particulate have been, and are, handled ina number of ways. For example, biofiltration swales, settling ponds,fluid/particle density separators, mechanical separators and mediaabsorbers and filters are employed to remove such types of contaminants.Swales and settling ponds take up significant real estate and aretherefore generally not particularly desirable in many settings. Theseparators require less space to operate, but are relatively costly andrequire considerable servicing on a regular basis. Existing absorbersand filter mechanisms may be effective at removing specifiedcontaminants; however, they tend to do so at the expense of flow throughrates. That is, the filtration efficiency is relatively low incomparison to the required water flow through desired. That may beacceptable under relatively low flow rates; but not so under relativelyhigh flow rates. More efficient systems such as the one described inU.S. Pat. No. 5,759,415 issued to Adams on Jun. 2, 1998, assigned toVortechnics, Inc. and entitled METHOD AND APPARATUS FOR SEPARATINGFLOATING AND NON-FLOATING PARTICULATE FROM RAINWATER DRAINAGE, have beendeveloped and employed to treat water in areas where treatment space islimited. However, regulations regarding the removal of suspended/finesolid particulates and/or dissolved and un-dissolved chemicalcontaminants have resulted in the need for supplemental removalarrangements.

There is an increasing need and requirement for separation systemsassociated with drain water and stormwater introduction to municipalwater handling systems and natural bodies of water to remove asubstantial portion of all forms of contaminants entering the municipalsystems or bodies of water at a point closer to the source. However, itis important that the separation systems not be prohibitively expensivein order to ensure that meeting those needs and requirements isfeasible. It is also of importance that such separation systems arerelatively easy to maintain. It is becoming increasingly important thatthese separation systems include means for removing suspended solidsand/or chemical contaminants, but without sacrificing the other desiredcharacteristics. Fluid filter systems that are configured to allow forloading of the filter by all floating and nonfloating particulatesrequire maintenance over relatively short intervals. In subsequent fluidtreatment cycles, contaminants that remain caked-on the filter surfacereduce fluid flow through effectiveness and must therefore be removedrelatively frequently. In addition, wet, caked filters are very heavyand therefore require the use of assistive equipment, such as cranes,when they are to be removed for maintenance.

Therefore, what is needed is a separation system and related method forremoving suspended and/or chemical contaminants from a fluid stream aspart of a separation system that may or may not be part of a largerfluid handling system, wherein the separation system is effective inaccommodating varied fluid flow rates. What is also needed is such aseparation system that is cost effective and configured for ease ofmaintenance, including, for example, addressing the limitations ofcontaminant retention on the filter and filter device weight thatshorten maintenance cycles and increase maintenance difficulty. Further,what is needed is such a separation system that includes a filter systemcapable of removing identified contaminants with minimal impact on fluidflow rates.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a separation systemthat is effective in accommodating varied fluid flow rates. It is alsoan object of the present invention to provide such a separation systemthat conforms or substantially conforms with established contaminantremoval requirements. Further, it is an object of the present inventionto provide such a separation system that is cost effective andconfigured for ease of maintenance. In that regard, it is an object ofthe present invention to maximize contaminant retention within thesystem while minimizing retention on the surface of the filter and toreduce filter device weight at the time of maintenance activities. Theseparation system preferably includes a filter system capable ofremoving identified contaminants with minimal impact on fluid flowrates.

These and other objectives are achieved with the present invention. Theinvention is a fluid separation system and related method for removingan array of contaminants from a fluid stream with minimal impact on thepassage of the fluid stream through the system. The method involves thetransfer of contaminated water through the separation system and theseparation of contaminants therein. The separation system includes afilter system arranged to remove suspended and/or dissolved contaminantsfrom the fluid stream.

The separation system is preferably established in a treatment chamberhaving an inlet, an outlet, one or more filter units, and a pretreatmentsump referred to herein as a containment chamber. The inlet may be indirect contact with a fluid or it may be connectable to an upstreamfluid transfer conduit. The outlet may be in direct contact with asurface water location or it may be connectable to a downstream fluidtransfer conduit. If applicable, the upstream fluid transfer conduit andthe downstream fluid transfer conduit may be part of a common municipalwater handling system. For example, the upstream conduit may beassociated with a drain arranged for water on a surface, such as aparking lot surface, to be removed from the surface, and the downstreamconduit may form part of the water transfer mechanism designed to divertthat water from the drain to a municipal treatment plant or naturalsurface waters. The separation system of the present invention isdesigned to remove contaminants from the water before the water reachesthe treatment plant or natural surface waters. The containment chamberof the separation system provides a means to remove much or all of thefloating and nonfloating particulates from the fluid prior to contactingthe filter unit, or alternatively, to allow for sloughing off of someportion of loaded contaminants from the filter unit in a manner thatkeeps the contaminants away from the filter unit. The filter unit of thepresent invention is designed for upward and/or radial flow of the fluidinto and through the filter unit. That configuration, coupled with theuse of the containment chamber, allows sloughing off of bulkcontaminants that may be retained thereon when the fluid flow subsides.As a result, the filter unit of the present invention experiences muchless contaminant loading over a given period as compared to priordevices that allow for loading of all or substantially all contaminantsto the filter system, or that otherwise impose excessive amounts ofcontaminants on the filter system. As a result, maintenance cycles arelengthened for the separation system of the present invention. Thefilter unit of the present invention further allows for any filter mediacontained therein to be released prior to removal of the filter devicefrom the treatment chamber. This allows for simple maintenance withoutthe need for assistive removal equipment.

In one aspect of the invention, a separation system is provided forremoving suspended and/or dissolved contaminants from a fluid. As noted,the system includes a tank having an inlet, an outlet, a confinementdeck, and a containment chamber below the confinement deck and one ormore filters removably retained to the confinement deck, wherein thefluid entering the containment chamber through the inlet passes throughthe one or more filters to the outlet, and wherein the one or morefilters are configured to remove a portion or all of the suspendedand/or dissolved contaminants in the fluid prior to the fluid passingthrough to the outlet. The outlet may be part of an outflow chamberabove the confinement deck, wherein fluid exiting the one or morefilters enters the outflow chamber before passing to the outlet. Theoutlet may also simply be any sort of container, port, flow conveyanceconduit, siphon conduit, opening, or arrangement in direct or indirectfluid communication with the filter unit discharge(s). The confinementdeck may include one or more openings to allow fluid entering thecontainment chamber under excess flow conditions to bypass the one ormore filters and pass to the outlet. The openings may include standpipesextending into the containment chamber and into the outflow chamber. Thenumber of filters employed may be selected as a function of desired flowrate and/or contaminant level and/or content of the fluid passing fromthe inlet to the outlet. The filters include a retainer with a floor anda perimeter retainer wall, either or both of which may be porous,arranged to define an interior retainer space in fluid communicationwith the outlet of the filter and arranged to allow fluid to flowthrough the perimeter wall into the interior retainer space. Theretainer may include a porous interior conduit spaced within theinterior retainer space and in fluid communication with the outlet. Inthat arrangement, the retainer may retain one or more filter mediawithin the interior retainer space but not within the interior conduit.The filter media may be releasably retained within the retainer. Forexample, the retainer floor may have one or more media retention plateshingedly affixed to the perimeter retainer wall. The filter unit mayalso include a housing containing the retainer therein. When a porousretainer perimeter wall is used, the housing is preferably spacedtherefrom to allow fluid to flow therebetween. The filter unit with thehousing may be configured for the retainer floor to have one or moremedia retention plates pivotably hinged to the housing perimeter wall.

In another aspect of the invention a method is provided for treating afluid to remove suspended and/or dissolved contaminants therefrom toproduce a treated fluid having the suspended and/or dissolvedcontaminants substantially removed. The method includes the steps ofdirecting the fluid to a confinement chamber of a tank wherepretreatment occurs, directing the pretreated fluid to one or morefilters, wherein the pretreated fluid passes into each of the one ormore filters radially and/or upwardly for treatment to produce thetreated fluid, and allowing the treated fluid to pass from the one ormore filters to an outlet. Additionally, the method may further includethe steps of releasably retaining within one or more of the one or morefilters one or more filter media. A method is also provided for removinga fluid, filter media, and/or contaminants from a separation systemhaving a tank with a containment chamber separated from and spaced belowan outlet by a confinement deck, wherein the confinement deck includesone or more releasably retained filter units, each retaining therein thefilter medium and removably retained, either by positioning withinfilter unit sockets therein, or by connecting to the confinement deck byother means. The method includes the steps of accessing the containmentchamber with removal means, removing a portion or all of the fluid,filter media, and/or contaminants contained within the containmentchamber, removing the one or more filter units from the confinementdeck, accessing the containment chamber through the filter unit socketsand/or any overflow means or port, such as a standpipe, and removing theremainder of the fluid, filter media, and/or contaminants from thecontainment chamber. The removal method may also include the steps ofreleasing the filter media from the filter units prior to the step ofaccessing the containment chamber with the removal means, inserting newfilter media into the one or more filter units released from theconfinement deck, and re-inserting the filled filter units into theconfinement deck sockets after the step of removing the remainder of thefluid, filter media, and/or contaminants from the containment chamber.

These and other features of the invention are set forth in theaccompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the separation system of the presentinvention, showing a partial cut-away view of the tank to expose thetank interior.

FIG. 2 is a perspective view of the interior of the tank of theseparation system showing a partial cut-away view of the confinementdeck with filter units.

FIG. 3 is a close-up perspective view of the confinement deck of theseparation system showing the standpipe and two filter units in partialcross-section.

FIG. 4 is a perspective view of a cylindrical version of the tank of thepresent invention.

FIG. 5 is an exploded view of the filter unit. FIG. 5A is a perspectiveview of the optional porous interior conduit. FIG. 5B is a perspectiveview of a first retainer floor door. FIG. 5C is a perspective view of asecond retainer floor door.

FIG. 6 is a perspective view of the filter unit of the presentinvention, showing a portion of the exterior of the retainer.

FIG. 7 is a perspective view of the filter unit showing a partialcut-away view of the housing and retainer to show the retainer filledwith filter media and showing the interior conduit.

FIG. 8 is a simplified elevation view of a cross-section of the filterunit of the present invention.

FIG. 9 is a perspective view of the filter unit shown retained in theconfinement deck with a partial cut-away view of the housing andretainer.

FIG. 10A is a perspective view of the housing from the top. FIG. 10B isa perspective view of the housing from the bottom.

FIG. 11 is a cross sectional view of the housing.

FIG. 12 is a perspective view of a portion of the separation system ofthe present invention, showing the interior of the tank including theconfinement deck and a plurality of filter units with media retentionplates open.

FIG. 13 is a perspective view of the separation system of the presentinvention, showing a partial cut-away view of the tank to expose thetank interior during filter unit removal from the containment chamber.

FIG. 14 is a perspective view of the separation system of the presentinvention, showing a partial cut-away view of the tank to expose thetank interior with filter units removed, and showing the access hatchopen for fluid and filter media removal.

FIG. 15 is an overhead view of the exterior of the separation tankshowing a removed filter unit thereon overturned for filter mediafilling.

FIG. 16A is a plan view of the separation tank of the present inventionshowing an alternative containment chamber outlet arrangement. FIG. 16Bis an elevation view of the separation tank showing the alternativecontainment chamber outlet arrangement of FIG. 16A.

FIG. 17 is an elevation view of an alternative embodiment of theseparation tank including a forebay.

FIG. 18A is a plan view of the separation tank of the present inventionshowing alternative positioning of the filter units with respect to theconfinement deck. FIG. 18B is a cross-sectional elevation view of theseparation tank showing the alternative filter unit positioning of FIG.18A at section A-A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A separation system 100 of the present invention is illustrated in theaccompanying drawings. As shown in FIGS. 1-3, the system 100 includes atank 110 having an outflow chamber 111 and a containment chamber 112spaced below the outflow chamber 111 by a confinement deck 200. Thecontainment chamber 112 includes a tank inlet port 113 through which afluid to be treated enters the containment chamber 112 from an inletconduit 120. The outflow chamber 111 includes a tank outlet port 114through which a treated fluid exits the outflow chamber 111 via anoutlet conduit 130. The tank 110 also preferably includes an accesshatch 115 for accessing the interior of the tank 110 at the outflowchamber 111, and a manhole 116 with cover 117. While the preferredembodiment of the present invention describes the separation system 100with a specific outflow chamber 111 above the confinement deck 200, itis to be understood that in an alternative embodiment, the fluid maypass from the containment chamber 112 through the one or more filterunits to be described herein directly to the outlet conduit 130 or someother form of treated fluid exit means.

The tank 110 is preferably made of concrete but may alternatively befabricated in whole or in parts of metal, plastic, such as fiberglass,or other suitable materials. It may be rectangular, round, oval or othersuitable shape. The inlet conduit 120 may be used to connect the tank110 to an upstream fluid transfer system. Similarly, the outlet conduit130 may be used to connect the tank 110 to a downstream fluid transfersystem. For example, the upstream fluid transfer system may include adrainage system from a roadway or a parking lot, or a preliminaryseparation system, and the downstream fluid transfer system may includea municipal water treatment plant or natural or artificial surfacewaters.

With continuing reference to FIGS. 1-3, the confinement deck 200includes one or more openings 210 that allow for overflow fluid to passdirectly from the containment chamber 112 to the outflow chamber 111under relatively very high fluid flow conditions. Preferably, the one ormore openings 210 retain therein a standpipe 220. The standpipe 220 alsoallows excess untreated fluid to pass directly from the containmentchamber 112 to the outflow chamber 111 without being treated, forexample when fluid flow rates through the inlet conduit 120 areexcessively high. However, the standpipe additionally builds drivinghead on one or more filter units 300 and preferably extends into thecontainment chamber 112 far enough to ensure that under such conditions,floating contaminants cannot pass directly from the containment chamber112 to the outflow chamber 111. The standpipe 220 may also be used as aportal for the removal of fluid and/or particulates from the containmentchamber 112 when accessed through the manhole 116. The confinement deck200 also includes one or more filter sockets 230 for removably retainingin each one thereof a filter unit 300. One or more filter clamps 240 areused for that purpose. In general consideration of the intendedoperation of the separation system 100, untreated fluid enteringcontainment chamber 112 passes through the one or more filter units 300where undesirable entrained and/or dissolved matter is filtered out. Thetreated water then passes out of the filter unit(s) 300 into the outflowchamber 111 from which it exits. While the tank 110 of FIGS. 1-3 isshown to be rectangular in shape, it is to be understood that the tankmay be of another shape, such as cylindrical, as shown by tank 110′ ofFIG. 4. The inlet to a tank such as tank 110′ may be arranged to imparta swirling motion of the fluid entering the containment chamber so as tofurther enhance separation of floating and non-floating matter bydirecting it to the center of the tank. The advantages of inducing fluidswirl are described in U.S. Pat. No. 5,759,415 issued to Adams on Jun.2, 1998, assigned to Vortechnics, Inc. and entitled METHOD AND APPARATUSFOR SEPARATING FLOATING AND NON-FLOATING PARTICULATE FROM RAINWATERDRAINAGE. The contents of that patent are incorporated herein byreference.

An important aspect of the present invention is the design of the filterunit 300. With reference to FIGS. 5-11, the filter unit 300 preferablyincludes a housing 301 with a housing lid 302 and a housing perimeterwall 303. The filter unit 300 further includes a retainer 305positionable within the housing 301. The retainer 305 includes aretainer perimeter wall 306, a retainer floor 307, and, optionally, aporous interior conduit 308. The housing lid 302 includes a dischargeport 309 at the top surface of thereof. The housing 301 optionallyincludes one or more lifting handles 310 for insertion and removal ofthe filter unit 300 with respect to the filter socket 230. The housing301 may be fabricated of any material, but is preferably fabricated of anonmetallic material, such as plastic. The housing lid 302 may be formedintegrally with the housing perimeter wall 303, or it may be removablyaffixed to the housing perimeter wall 303. The housing 301 is designedto be easily insertable into and removable from the filter socket 230 ofthe confinement deck 200 for ease of maintenance of the tank 110 as wellas the filter unit 300. A gasket 304 may be employed to seal the housing301 to the confinement deck 200. In an alternative embodiment of theinvention, there may be no housing perimeter wall 303, with the retainer305 simply affixed to the lid 302 and provided with an outlet forpassage of treated fluid either to the outflow chamber 111 or some otherfluid transfer means. When in position in the socket 230, the housing301 extends into the containment chamber 112, thereby acting to blockfloating contaminants from reaching the retainer 305. However, if thereis no housing perimeter wall 303, such floating contaminants will beretained by the retainer 305. For purposes of this description, thehousing perimeter wall 303 may effectively be the retainer perimeterwall 306 when only up flow of the fluid is desired.

The retainer perimeter wall 306 and the floor 307 define an interiorretainer space 319 into which fluid to be treated passes. The interiorretainer space 319 is in fluid communication with the outlet 114 of thetank 110. The retainer perimeter wall 306 of the retainer 305 preferablyincludes an upper retainer wall flange 311 for affixing the perimeterwall 306 to the housing lid 302. For upflow of fluid into the retainer305, the floor 307 is porous. For radial flow into the retainer, theretainer perimeter wall 306 is porous. In particular, in order tomaximize fluid flow conditions, the retainer perimeter wall 306 isporous and is spaced from the interior of the housing perimeter wall 303to create a space for fluid to enter the housing around the perimeter ofthe retainer 305 prior to entering it through the retainer perimeterwall 306. If upflow and radial flow are desired, the retainer perimeterwall 306 and the floor 307 are both porous. The porous interior conduit308 is only required if one or more filter media are employed to removecontaminants. When in use, the porous interior conduit 308 of theretainer 305 includes a conduit mounting flange 312 for affixing theporous interior conduit 308 to the housing lid 302 preferablyapproximately centered in relative position to the discharge port 309 ofthe housing lid 302. Thus, in this embodiment of the filter unit 300,the retainer perimeter wall 306 and the interior conduit 308 are notconnected together but are instead separately connected to the housinglid 302. The retainer perimeter wall 306, the floor 307, and theinterior conduit 308 may be fabricated of metallic or nonmetallicmaterial. When made porous, they may be made as perforated, corrugated,or pleated screening elements, or other configuration as selected by theuser.

With continuing reference to FIGS. 5-11, the interior of the housingperimeter wall 303 preferably includes a means for releasably retainingthereto a rotatable release rod 316 that extends through a housing lidhole 315 of the housing lid 302. The means for releasably retaining maybe a retaining clip (not shown) to which the release rod 316 may beclipped and allowed to rotate therein. The rotatable release rod 316terminates at a first end thereof with a release handle 317 adjacent tothe housing lid 302, and at an opposing second end thereof in aretention leg 318. The retention leg 318 is designed to fix the retainerfloor 307 in a first position when the filter unit 300 is operational,and in a second position when the filter unit 300 is undergoingmaintenance. The retention leg 318 may be rotated between the first andsecond positions by rotating the release handle 317.

As noted, the space defined by the retainer perimeter wall 306, theoptional interior conduit 308 if used, and the retainer floor 307defines the interior retainer space 319 within which one or morefiltering media 320 may be located. The one or more filter media mayinclude perlite, zeolite, granular activated carbon, peat, or othersuitable filter media selectable as a function of the contaminants to beremoved. The filtering media 320 are preferably selected for theireffectiveness in removing entrained and/or dissolved matter from thefluid to be treated, but that allow the fluid to pass from the outsideof the retainer 305 to the interior of the interior conduit 308 atspecified flow conditions. Combinations of different filter media may beemployed based on porosity, contaminant affinity, and the like. Suchcombinations may be mixed or layered, either vertically or horizontally.The porosity of the retainer perimeter wall 306, the retainer floor 307,and the interior conduit 308 must also be designed with both objectivesin mind. In some instances, tightly packed filter media and/orrelatively small pore sizes for the retainer 305 may be required ordesired, whereas in other instances, loosely packed and/or large poresizes for the retainer 305 may be required. It is to be noted that theretainer 305 may be used without any filter media 320 in thosesituations where it acts as a gross filtering device for separatingrelatively large particulates from the fluid prior to entering theoutflow chamber 111 (or other form of outlet arrangement). In anarrangement in which there are no filter media 320 used, the interiorconduit 308 is not required and the retainer 305 simply includes theretainer perimeter wall 306 and the retainer floor 307. In anarrangement in which the filter media 320 are used in an up flow onlysystem, a top screen may be used to block the filter media 320 fromescaping into an exit space 360 prior to discharge, wherein the topscreen and exit space 360 effectively act as an interior conduit.

An important aspect of the design of the retainer 305 for the purpose ofmaintaining the filter unit 300 as well as the system 100 is thearrangement of the retainer floor 307. As shown in FIG. 5, the retainerfloor 307 is preferably a hinged structure and more preferably, acenter-hinged structure. The retainer floor 307 includes a pivot shaft321, a first media retention plate 322 hingedly connected to the pivotshaft 321, and a second media retention plate 323 hingedly attached tothe pivot shaft 321. Each of media retention plates 322 and 323 includesa perforated or porous body 325 and an optional outer flange 326. Themedia retention plates 322 and 323 are selected and designed to providestructural support for any filter media to be retained by the retainer305, and to withstand the hydrostatic pressure to be experienced whenthe filter unit 300 is in use. The pivot shaft 321 pivots and isretained in openings 328 of the housing perimeter wall 303. The retainerfloor 307 may be fabricated of metallic or nonmetallic material. In anarrangement where there is no housing 301 but only retainer 305, themedia retention plates 322 and 323 may be retained in place by insertingthe pivot shaft 321 into opposing holes of the retainer perimeter wall306. In that arrangement, the release rods 316 and the release handles317 may be employed to releasably retain the media retention plates 322and 323 in place until the filter media are to be released. Further, ifthere are no filter media 320 to be used, the hinged media retentionplates 322 and 323 are unnecessary and the retainer floor 307 may bereleasably or permanently affixed to the retainer perimeter wall 306.

In operation, the system 100 enables the removal of undesirable matterfrom the fluid stream during the fluid's passage from the inlet conduit120 to the outlet conduit 130. Untreated fluid 330 entering thecontainment chamber 112 fills that containment chamber 112 and reachesthe underside of the filter unit 300 during which time floating andnon-floating contaminants are separated from the pretreated fluidreaching the underside of the filter unit 300. This produces hydrostaticpressure on the filter unit 300, thereby forcing the pretreated fluidinto the retainer 305. Preferably, floating and non-floatingcontaminants of relatively large size remain trapped in the containmentchamber 112 by the housing 301, the retainer perimeter wall 306, thestandpipe 220 or any combination of one or more thereof. As shown inFIGS. 3 and 8, the pretreated fluid 330 enters the housing 301 throughthe retainer floor 307. As hydrostatic pressure increases on the filterunit 300 with the filling of the containment chamber 112, the pretreatedfluid 330 moves into radial flow space 340 between the housing perimeterwall 303 and the retainer perimeter wall 306. The pretreated fluid 330enters space 319 by way of both the retainer perimeter wall 306 viaradial flow space 340 and directly through the perforated body 325 ofthe retainer floor 307. If there are no filter media 320 in space 319,the fluid-under-treatment 350 passes directly through the space 319before exiting the discharge port 309 into the outflow chamber 111. Itis anticipated that entrained relatively larger particulates will betrapped by either or both of the retainer perimeter wall 306 and theretainer floor 307. If there are filter media 320 in space 319, thefluid-under-treatment 350 dwells in space 319 for trapping entrained,suspended, and/or dissolved contaminants before passing through interiorconduit 308 into exit space 360 and exiting the discharge port 309 intothe outflow chamber 111. When the pretreated fluid 330 in thecontainment chamber 112 recedes, contaminants trapped on the exterior ofthe retainer 305 and/or the housing 301 are more likely to drop backinto the containment chamber 112 rather than remain caked on. Thisenhances the chance of the filter unit 300 remaining sufficiently clearto conduct subsequent filtering operations without the need to halt thefluid transfer process for filter unit 300 maintenance.

As illustrated in FIGS. 12-15, the design of the system 100 of thepresent invention enables effective treatment of a fluid as well as easeof maintenance of the system 100 itself. The process of maintaining thesystem 100 when the filter media 320 are in use includes the step ofreleasing either or both of retainer media retention plates 322 and 323to allow the filter media 320 to fall into the containment chamber 112.That releasing step may be accomplished by rotating the release handles317 to the second position to allow the hinged media retention plates322 and 323 to pivot about the pivot shaft 321. If no filter media areused, this step may be omitted and, in fact, hinged media retentionplates 322 and 323 are not required as there is no need to remove filtermedia 320 therefrom. In the next step, pretreated fluid, trappedcontaminants, and any released filter media are removed from thecontainment chamber 112 using removal means, such as vacuum means, todraw out the pretreated fluid, trapped contaminants, and any releasedfilter media. This removal may be achieved by inserting the removalmeans into the manhole 116 and through the standpipe 220, or port 210 ifthere is no standpipe 220. Either while undertaking the removal step orthereafter, the one or more filter units 300 retained to the confinementdeck 200 in filter sockets 230 may be removed by releasing filter unitclamps 240, shown in FIGS. 1 and 12, fixed against the housing lid 302(or by other means of connection to the confinement deck) and removingthe filter units 300 from the confinement deck 200, preferably usinglifting handles 310. The filter units 300 in situ may be accessed viaaccess hatch 115. This method of removing the filter media 230 from theretainer 305 prior to removing the filter unit 300 substantially reducesthe weight of the filter unit 300 to be maintained, thereby allowingsuch removal without using assistive mechanical equipment, such as acrane.

Upon removal of the one or more filter units 300 from the confinementdeck 200, the same or additional removal means may be used to removeuntreated fluid and/or filter media from the containment chamber 112.That additional removal step may be achieved by inserting the removalmeans into the access hatch 115 and through the one or more sockets 230to access substantially all of the interior of the containment chamber112. As shown in FIG. 15, the removed filter unit 300 may be invertedsuch that it rests on housing lid 302. A new batch of filter media maybe inserted into space 319 via either or both of open media retentionplates 322 and 323. The door(s) 322 and/or 323 may then be closed byrotating the release handles to the first position to clamp the door(s)322 and/or 323 into the retained position(s). The filled and closedfilter unit(s) may then be re-installed in the confinement deck 200, theaccess hatch 115 closed, and the system 100 made available for treatingthe fluid.

An additional optional step of the filter method of the presentinvention involves draining down the fluid within the containmentchamber 112 to keep the filter media 320 relatively dry under low or noflow conditions in the containment chamber 112. For that step, acontainment chamber outlet 400 is positioned in the containment chamber112 as shown in FIGS. 16A and 16B. The containment chamber outlet 400also acts as the outlet for the outflow chamber 111 via outlet port 401that provides fluid communication from the outflow chamber 111 to thecontainment chamber outlet 400 through confinement deck 200, effectivelyreplacing outlet conduit 130. An optional containment chamber downspout402 may be included in that arrangement to trap floating particulateswhile allowing fluid to pass from the containment chamber 112 to theoutlet 400. Flow control means such as perforations 403 of the downspout402 enable regulation of the flow of fluid out of the filter unit(s) 300when flow into the containment chamber 112 subsides. In operation, thesystem of FIGS. 16A and 16B allows pretreated fluid to flow into thecontainment chamber 112 as previously described. The standpipe 220 alsoallows for pretreated fluid under relatively higher flow conditions tobypass the fluid unit(s) 300, also as previously described. However, theoutlet 400 in the containment chamber 112 positioned below the undersideof the confinement deck 200 ensures that the standing fluid surface inthe containment chamber 112 is below the bottom of the filter media 320.If there is a housing 301, the outlet 400 is preferably positioned sothat the standing fluid surface is just below the bottom of the filtermedia 320 but just above the bottom of the housing 301. This arrangementkeeps previously separated floatables confined in the containmentchamber 112 and away from the filter media 320. Treated fluid passingthrough the filter unit(s) 300 exit the discharge 309, passes along theupper side of the confinement deck 200, and then drops down into theoutlet port 401 to the containment chamber outlet 400 for discharge.

Another alternative arrangement of the system 100″ shown in FIG. 17includes a pre-treatment forebay 500 to isolate the tank inlet conduit120 from the containment chamber 112″ when the outlet conduit 130 cannotbe positioned above the inlet conduit 120, or when confinement of grosspollutants away from the filter units 300 is desired. In that situation,the forebay 500 is partially spaced from the containment chamber 112″ bya baffle 501, and completely isolated from the outflow chamber 111″ bytank wall 502. A forebay outlet conduit 503 provides the passageway forfluid entering the forebay 500 to enter the containment chamber 112″ viaintermediate space 504 that forms part of the containment chamber 112″when the fluid reaches and exceeds the standing fluid level 505. Theinlet of the forebay outlet conduit 503 is submerged and sealed to thebaffle 501 such that floatables are retained in the forebay 500. Undervery high flow conditions, the fluid rises to the level of the top ofthe baffle 501 and drops over it into the intermediate space 504 withoutreaching the outflow chamber 111″. The baffle 501 also retains floatingparticulates, at least until the fluid flow rate causes the fluid levelin the forebay 500 to exceed the top of the baffle. From there, theuntreated fluid is subject to the same filtering process previouslydescribed. It is preferred for this arrangement that a forebay manhole506 be provided directly over the forebay 500 to allow for removal ofexcess contaminants without directly reaching the containment chamber112″. Although not shown, the tank 110″ of system 100″ may include astandpipe for bypass, also as previously described.

An alternative arrangement of the filter units 300′ with respect to amodified confinement deck 200′ is shown in FIGS. 18A and 18B as part oftank 600. The filter units 300′ are positioned substantially in theoutlet chamber 111 rather than substantially in the containment chamber112. Each of the filter units 300′ is in fluid communication withpretreated fluid of the containment chamber 112 through a filter port601. Each filter port 601 is preferably sealed such that pretreatedfluid only enters the filter unit 300′ therethrough. The filter units300′ include modified housings 301′ including a housing perimeter 306′and a housing floor 307′. The housing floor 307′ includes a port 350 influid communication with the confinement deck port 601 that isconfigured to ensure that the pretreated fluid entering the filter units300′ is forced to pass into filter area 320 for either or both of upwardand radial flow. The filtering of the fluid upon entering the filterunit 300′ is achieved in the manner previously described with respect tofilter unit 300. The alternative arrangement of tank 600 enables theplacement of more filter units 300′ in a defined area, it limits wettingof the filter media when the fluid subsides, and the sealing of thefilter units 300′ with respect to the confinement deck 200′ may beeasier to achieve. The filter units 300′ may include a filter outletextension 360 to assist in drawing treated fluid out of the filter units300′.

It is to be understood that the above-described steps are intended torepresent primary aspects of the invention and that additional steps maybe implemented. Further, the order of the steps illustrated as part ofthe process is not limited to the order described herein, as the stepsmay be performed in other orders, and one or more steps may be performedin series or in parallel to one or more other steps, or parts thereof.Additionally, in an alternative embodiment of the filter unit 300, theretainer 305 is the only component of the filter unit 300 that isremovable, whereas there is either no housing 301 and the retainer 305is affixed directly to the confinement deck 200, or the housing 301 ispermanently affixed to the confinement deck 200.

While the present invention has been described with particular referenceto certain embodiments of the separation system, it is to be understoodthat it includes all reasonable equivalents thereof as defined by thefollowing appended claims.

1-53. (canceled)
 54. A method of removing suspended and/or dissolvedcontaminants from storm water runoff, the method comprising: utilizing atank having an internal deck that establishes a containment chamberbelow the deck and an outflow chamber above the deck, the tank includingmultiple filter units, each filter unit removably retained in arespective filter socket in the deck, each filter unit extending belowthe deck into the containment chamber; directing storm water into thecontainment chamber; head pressure causing the storm water to movethrough the filter units for filtering and upward out of the filterunits into the outflow chamber; flowing the storm water from the outflowchamber to an outlet of the tank.
 55. The method of claim 54 includingthe step of building up head pressure by providing a head building spaceabove the deck and collecting some storm water in the head buildingspace.
 56. The method of claim 54, further comprising: supporting eachfilter unit in its respective socket via a top portion of the filterunit and utilizing a gasket for sealing the top portion in the filtersocket.
 57. The method of claim 54 including the step of imparting aswirling motion to water in the containment chamber.
 58. The method ofclaim 54 wherein water travels radially into the filter units and thenupward into the outflow chamber.
 59. The method of claim 54 includingproviding a flow path for permitting water to flow through the tankwithout passing through the filter units under higher flow conditions.60. The method of claim 54, further comprising the step of performing amaintenance operation on the tank that involves removing at least someof the filter units from their respective filter sockets.
 61. The methodof claim 54, further comprising the steps of: keeping each filter unitin a secured state in its respective filter socket during storm waterflow; performing a maintenance operation that includes the steps of:releasing at least some of the filter units from their respective filtersockets; moving the released filter units upward out of their respectivefilter sockets; accessing the containment chamber through at least oneof the filter sockets to remove contaminants from the containmentchamber; placing replacement filter units into the filter sockets; andsecuring the replacement filter units in place in the filter sockets.62. The method of claim 61 wherein contaminants are removed from thecontainment chamber via a vacuum.
 63. A method of removing suspendedand/or dissolved contaminants from storm water runoff, the methodcomprising: utilizing a tank having an internal deck that establishes acontainment chamber below the deck and an outflow chamber above thedeck, the tank including multiple filter units, each filter unitremovably retained in a respective filter socket in the deck, eachfilter unit extending below, the deck into the containment chamber, eachfilter unit including a top portion supporting the filter unit in itsrespective socket; directing storm water into the containment chamber;building a head pressure to cause the storm water to enter and moveupward through the filter units for filtering and then out of the filterunits into the outflow chamber; flowing the storm water from the outflowchamber to an outlet of the tank; and causing at least some contaminantscaptured by the filter units to drop back into the containment chamber.64. The method of claim 63 wherein the step of building head pressureinvolves collecting some storm water in a head building space above theinternal deck.
 65. The method of claim 63, further comprising: utilizinga gasket in connection with each filter unit for sealing the top portionin its respective filter socket.
 66. The method of claim 63 includingthe step of imparting a swirling motion to water in the containmentchamber.
 67. The method of claim 63 wherein water travels radially intothe filter units and then upward into the outflow chamber.
 68. Themethod of claim 63 including flowing some storm water through the tankwithout passing through the filter units under higher flow conditions.69. The method of claim 63, further comprising the steps of: keepingeach filter unit in a secured state in its respective filter socketduring storm water flow; performing a maintenance operation thatincludes the steps of: releasing at least some of the filter units fromtheir respective filter sockets; moving the released filter units upwardout of their respective filter sockets; accessing the containmentchamber through at least one of the filter sockets to removecontaminants in the containment chamber; placing replacement filterunits into the filter sockets; and securing the replacement filter unitsin place in the filter sockets.
 70. The method of claim 69 whereincontaminants are removed from the containment chamber via a vacuum.